The present invention relates to a light source whose exit beam has a high energy density of the type composed of a lamp having a cold light mirror, and a heat protection filter in the optical beam path with cooling being provided for the heat protection filter.
Numerous photochemical and photobiological processes require high illumination intensities of monochromatic or quasimonochromatic radiation. The radiation dose for psoriasis treatments, for example, as well as for light radiation treatments in the oral cavity, is about 1 J (joule)/cm.sup.2 (see, for example, Zeitschrift fulr Experimentelle Chirurgie und Chirurgische Forschung [Journal for Experimental Surgery and Surgical Research] (1974) 9-17). If the irradiation periods are to be kept short, the radiation intensity must lie in the order of magnitude of 50 mW/cm.sup.2.
Spectral lights can not be used for this purpose because they have too large a luminous volume and their light cannot be sufficiently focused. Although it is possible to produce monochromatic or quasimonochromatic light from white dot-shaped light sources with the aid of grid or prism spectrographs, this approach does not permit the desired illumination intensities to be produced due to the required slit-shaped illumination. Moreover, the necessary optical equipment is expensive.
High illumination intensities could easily be produced with lasers, but a high energy argon laser and a liquid laser would be required to cover the visible spectral range. The costs and apparatus required for this would be considerable. There also exist cases in which the illumination is intentionally to be done only with incoherent light and not with the highly coherent laser light, for example, when measuring and observing the breathing openings in leaves.